Currently, exhaust gas purifiers that employ a diesel particulate filter (DPF) as a device to remove particulates contained in exhaust gas, such as particulate matter (PM), are put to practical use. During use of such exhaust gas purifiers, particulates such as PM deposit in the DPF, and accordingly, regeneration of the DPF is required. As methods of regenerating the DPF, for example, Japanese Laid-open Patent Publication Nos. 2006-140063 and 4-179817 and Japanese Patent No. 4995351 propose methods that employ high-frequency electromagnetic waves, such as microwaves, radiated from a microwave applicator. According to such methods, the DPF is exposed to electromagnetic waves such as microwaves to heat and burn particulates such as PM deposited on the DPF, so that the DPF is regenerated.
Microwave applicators are also employed in food warmers that heat food, chemical reactors, etc. Further reference may be made to Japanese Patent No. 2689722 and Japanese Laid-open Patent Publication No. 2002-70530 for related art.